Introduction
In this essay, a research took place about the following topics, which are meant to be clarified: geographic evidence as support of the theory of continental drift, scientifical acceptance of the movement of continents, the process of the scientific method and theory development, the scientific method help in understanding the natural world, association between the plate tectonics, continental drift and natural landforms.
With these topics addressed, in this essay, the understanding of the natural world should become clearer, adding new knowledge on the matter, which should complement the one acquired al throughout the course.
- Geographic evidence collected in the last part of the 20th century to support the theory of continental drift.
In the last part of the 20th century, four main areas of evidence seemed to support the theory o continental drift:
- The research made by the ship Atlantis, in 1947 showed that the floor of the Atlantic Ocean had a layer of sediments that a much smaller thickness than what was originally expected. Since it has been acknowledged that oceans should be dated of 4 billion years, this layer should be thicker, leading to the hypothesis of the existence of plate tectonics; and, by the 1950’s, more explorations done in the oceans revealed the existence of a massive mountain range on the floor of the ocean, expected to circle the entire planet (the global mid-ocean ridge);
- Also in the 1950’s, scientific exploration with magnetometers revealed the existence of magnetic variations on the floor of the ocean, since its’ main rock – basalt – has magnetite. If it is taken in count that it was recognized that rocks can be identified, according to magnetic properties, as having normal or reversed polarity (same as, or opposite polarity of, respectively, Earth’s present magnetic field), these last ones would indicate that there were times when, at the cooling of magma that formed them, the Earth’s polarity would not be the same. Further investigation revealed a pattern of stripes in each side of the mid-ocean ridge, normal and reversed;
- This lead to the hypothesis of ocean crust renovation. In 1961, theories began to emerge of mid-ridges being points where the oceanic crust was weaker and broken, giving way to new magma, which would cool down with the magnetic minerals positioned according to the Earth’s polarity at the time; and these ridges would be the limits of the later called plate tectonics. Furthermore, post-World War II oil explorations were made by ocean drilling. In 1968, after one of these drillings, made by the vessel Glomar Challenger in the Mid-Atlantic Ridge between Africa and South America, paleontologic studies dated the samples, proving the hypothesis of ocean crust spreading an renovation;
- With the improvement of seismic measuring technology and its’ use, it was acknowledge that there were areas of concentrated seismic activity; these areas were mainly located on the ridges and trenches. With the Worldwide Standardized Seismograph Network (WWSSN), these studies grew even more, giving even more precise locations for these areas. Linking the ocean floor spreading and renovation with these areas of bigger seismic activity led to the confirmation of ocean crust formation in the ridges and crust sinking in the trenches.
- Why do scientists today accept the movement of continents but not back in Wegener’s time?
However, back in Wegener’s time, his theory was rejected by the scientific community, because of several factors:
- Geophysicists at the time proved that the force produced by tides was not strong enough to be able to move continents; furthermore, the tidal force necessary to do so would be so big it would destroy the planet; if there was no known force that would be responsible for continental movement, the idea didn’t seem to make sense;
- Geologists, at the time, didn’t have enough knowledge, nor interest to study about ocean basins; the oil was taken from land drilling ashore. Also, their main purpose was to find oil and gas, and not to understand the planet’s history and way of functioning;
- Thus, Wegener, behind ahead of his time, had a group on non-related observations, with no way of confirming such; this went against the scientific knowledge development of the time, not being taken in consideration;
- Wegener didn’t also have any geological training. At the same time, not following any previous idea and being too young, in his thirties, little credibility was given to his theory;
- Geology revolved around interests at the time, so little tolerance and will to accept new ideas was given by the scientific community.
- The process of the scientific method and theory development.
Analyzing the process of the scientific method and theory development, and giving as an example, Wegener’s theory, one can say that the scientific method relies on:
- Observation;
- Prediction;
- Test/Experiment;
- Generalization.
The scientific method collects a series of data, by measuring or observing, which make them quantitative and qualitative, respectively; the results scientists get in the end will then be molded into theories, so it becomes important to have the ability to predict findings’ implications, which is called inductive reasoning, or induction.
Wegener is an example: it shows that he, after observing the existence of the same fossils in different continents, or the fit between South America’s and Africa’s shelves, that these places must have been joined together before.
However, the scientific community remains very conservative, not being very open to new ideas immediately and careful when interpreting the results. So, more than one experiment, or series of experiments, are required to be repeated.
The repeated same results will, then, form a strong basis to defend the new idea and establish a new paradigm – this is called a paradigm shift that takes place once these conditions are met.
This way, a theory is formed, like the one of Wegener, only established in the 20th century.
- How does the scientific method help us understand the natural world?
Science has always had as its’ objective to be able to explain nature. Thus, the scientific method was designed, so that it would be possible.
According to the scientific method, nature is first observed and measured. This is now possible due to all the evolution of exact sciences and technology. The data collected (observations and measurements) allows scientists to build models of nature, with which they can isolate what they want to study. Thus, they can induct on why some phenomenon and through what process.
Then, with the model they have to study and the hypothesis, they can then develop and perform a series of experiments to test if, in the model, the same thing happens, as it does in nature. If it does, those series of tests can be repeated, improved and double-tested, so that a base of solid facts can be provided that support the findings’, or results’, interpretation and, this way, extrapolated to nature, helping to understand how nature works, and what is its’ logic.
- How plate tectonics provides the mechanism for continental drift.
Plate tectonics constitutes a theory that takes in count all the scientific finding about the ocean floor, seismic activity and geology that helped prove Wegener’s theory right for continental drift.
For such, the plate tectonics theory defends that the ocean floor does suffer spreading, influenced by currents on the mantle layer of hot rock that make melted rock emerge from the ridges’ areas, where it cools and forms new crust.
Furthermore, it says that the planet’s crust is divided in six main pieces, which are called plates, and some smaller ones, too. Each plate is constituted of a portion of ocean and land (continent and/or islands).
Limiting the plates, the mid-ridges can be found, in which new crust is formed, causing those plates to move apart, while in the ocean trenches and young mountains, the same plates unite and the older crust dives bellow the other and goes back to Earth’s interior; besides this, large faults can be observed in places where two plates move with horizontal orientation between them.
- How do plate tectonics explain the process of continental drift?
If taken in consideration the basics of plate tectonics, each continent may be formed by one, or more than one plate.
The plates, limited by the mid-ridges, are being separated from each other, by crust formation on the ridges, being brought together, with one sinking bellow the other and slide between them.
The continents, being formed by one or more plates, move along with them. Relating them with each other, they are also drifting apart, getting close and sliding horizontally. They move in relation with one another.
Thus, through these three kinds of movement of the plates, the continents actually drift, explaining this theory, so ridiculed in Wegener’s time.
- How do plate tectonics explain natural landforms like the Himalayas and the Ring of Fire in the Pacific Ocean?
Natural landforms’ formation, like the Himalayas or the Ring of Fire, can be explained by the plate tectonics. According to such theory:
- The area where the Himalayas are now located constitutes a zone where two plates gather: Indo-Australian and Eurasian plates. Having a crust with less density, there is no subduction; instead, they crawl on the top of one another, overriding themselves, having a so called collisional boundary, where there is a convergence between them. Thus, a mountain range, the Himalayas, is formed.
- “The Ring of Fire” is located on the margins of one important plate – the Pacific Plate. In this area both active and dormant numerous volcanoes and zones of frequent strong earthquakes can be found, in an area that comprehends New Zealand, Indonesia, Japan and Kamchatka (Russia). On this zone, subduction occurs, explaining the strong seismic activity, since plates sink bellow others, causing great forces to be done and released high energy.
Conclusion
The understanding of how nature works and forms its’ wonders has been studied by scientist for quite some time now, even in times when there wasn’t enough technology and development to support theories, like the one Wegener came up with.
With technological advances and using the scientific method as basis, models of nature could be built and nature could be studied more thoroughly, now with good solid facts, given by series of experiments.
Thus, one could learn that Wegener was actually right and ahead of his time, and that our planet’s crust is in constant change.
Understanding the processes by which such changes occurred in the past and are occurring now, permits one to see some nature’s marvels with more enlightened vision.
References
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